University tables, or more specifically the rankings system we employ, generate a fair amount of anger in the academic community. Institutions are often annoyed at the methodology and the data we choose, and at the sheer gall of marking them against each other in the first place. But we believe that, on balance, tables like these are important.

Students emerge from their studies deeper and deeper in debt each year, and from 2006, when the tuition fees legislation bites, courses will all come at a price. So it's important students know what they are getting for their cash.

In the absence of a systematic and quantifiable method of judging courses, and ahead of the student satisfaction surveys currently being proposed, we reckon there is a place for a resource such as this in the students' armoury when picking a course and a place to study it from the thousands available. But there's a right and a wrong way to use university tables, so here's how not to do it.

· Don't use just the tables. They are a guide to teaching quality. They won't tell you what the beer is like, whether the halls smell funny, or how trendy your future friends might be. Nor will they fill you in on the clubs, societies, weather or the number of hills you'll have to climb to get to lectures. Still less will they tell you the make-up of your course or the chances of getting a PC in the computer room. They are simply a snapshot of part of the student experience.

To get the full picture, go to open days, talk to students and teachers, read prospectuses. We've even heard there are other university tables that give a slightly different view ... The Quality Assurance Agency reports on individual universities and departments. We don't use those reports in the tables because they are neither comprehensive nor quantifiable, in that they score departments only as "excellent" or "satisfactory". But they should be a part of your research and you can find them on qaa.ac.uk

· If you stumble across tables produced by other newspapers, you may notice the results are sometimes startlingly different. The reason is that we use different methodology and different data so, naturally, we have different conclusions. Our tables have been compiled by Campus, a department of Brunel University.

The online versions of the Guardian tables give you the chance to pick the indicators that mean most to you and to alter the tables accordingly. So if you think job prospects are fundamental to a business studies course, you can make them so.

· The overall rankings are interesting, but please don't regard them as decisive. They're certainly handy ammo with which to deride your mates who are off to a university further down the list, but pub banter is their best use. It matters not that a university is in the overall top rankings, if it teaches your own subject badly or not at all.

· Don't be a snob. Many of the universities that do well in these tables are no surprise - the top names have the money and status to excel in all sorts of areas. But there is excellence just about everywhere. Universities you have barely heard of are more than likely to teach your chosen subject very well indeed. So when you come across a former polytechnic at the top of a subject table, don't hoot with derision and assume the whole thing is flawed. The status quo isn't forever and universities do improve and decline over time.

· Remember these tables are (deliberately) limited. They are for undergraduates doing full-time degrees at universities and HE colleges. There's nothing for postgraduates here. We haven't included research data, because these are, quite simply, teaching tables. Many argue that we should include scores from the 2001 research assessment exercise, but we're sticking to the undergraduate data because that's the way we like it. While having cutting-edge research performed at your university is good for the institution as a whole, there is no consistent evidence to suggest it will improve your personal learning experience. You may be lucky and share in the research or you may find your tutor is too engrossed in work to teach you properly. Anecdotal evidence points both ways so we've simply left it out. If it's research ratings you want, look at EducationGuardian.co.uk/researchratings.

· And one small extra caveat. We've done our best in the consultative process, and all universities were asked by the Higher Education Statistics Agency (Hesa) to check the data we have on them. Many responded and we've done our best to make all the changes they have asked for. But there's a significant group of universities who will splutter over their cornflakes this morning and get in touch to correct figures. If you contact education.editor@guardianunlimited.co.uk, those changes will be made on our website and may well affect the rankings (the site contains fuller tables, not just the top rankings, so you should check it out anyway).

· Jimmy Leach is editor of the Guardian University Guide 2005. He and Rosa Scoble of Campus will be online to discuss the tables this Friday at 3pm. EducationGuardian.co.uk/talk